Rating 2011's new team of bicycles

Gear

Two wheels and pedals, a handlebar, frame, chain and derailleur gears. The bicycle's basic design is so simple and efficient that it hasn't really changed for more than 75 years. But the relentless human urge to improve produces annual refinements in bikes — and maybe none push the envelope like the 2011 models examined below.

Likes: It's the coolest-looking, most comfortable, best-handling bike on the block. Builder Jeff Jones, a former GT designer, has rejected conventional concepts of suspension and lean-forward body positioning, which he says is unnatural for non-racers who don't care about aerodynamics. His new geometry shrinks the cockpit, slides the seat farther back over the rear wheel and uses easy-reach handlebars to put riders in an upright horseback-type position. That puts more body weight over the pedals, taking weight off the hands (eliminating numbness). This position enables the feet and legs to share suspension duties with the flexible frame and wheels. The frame uses seat stays that run all the way from rear axle to the head tube, which allow the seat tube to flex back and down. The triangulated fork is actually stiffer than a regular rigid fork, but the giant low-pressure fat front wheel and Surly tire swallow bumps. You get great stability from the bike's low crankshaft and your ability to change hand positions on the multi-position handlebar. Put on skinnier tires and it flies on asphalt.

Dislikes: If you aren't social, you will not like being continually stared at and talked to.

Likes: Besides the superb commuter features — comfortable upright positioning, fenders, rack, kickstand, enclosed chain to keep pants grease-free and battery-free lights powered by the front hub that stay on for 20 seconds after you're stopped — the big story here is the smooth, seamless shifting. Instead of clicking through eight, nine or 10 gears, as with normal derailleur systems or internally geared hubs, the NuVinci 360 uses a maintenance-free "planetary" design, with a set of internal spheres that transfer power with the slightest twist of a handlebar grip. The top-end and bottom-end ranges are a bit narrower than you might find on a performance mountain or road bike but are ideal for commuting. A visual indicator on the twist shifter, which changes from a flat to a hilly profile, gives you an idea of what gear you're in.

Dislikes: There was a little bit of gear slippage at high torque; I kept having to retwist on hill climbs. And fixing a flat will be a hassle given the lack of a quick-release on the rear hub and the need for tools and minor disassembly.

Likes: Front shifts are instantaneous and can be done under load and while climbing. Derailleur maintenance is eliminated. The chain won't break or be dropped during shifting. Being smaller in diameter, it has better clearance over rocks than standard rings. The chain is shorter (and lighter), and there's no real weight penalty. There are a few similar systems, but not for performance riding. The rest of the bike, featuring a 10-speed hub and Diamondback's four-bar "knucklebox" rear suspension design, ain't bad either; it's a nimble, solid bump-eater with minimal energy-sapping suspension bob.

Dislikes: As a two-ring replacement, the HammerSchmidt lacks granny-gear turnover on steep climbs — so I walked more than usual. And it isn't cheap, adding around $500 to the price tag.

Price: $3,800. (253) 395-1100; http://www.diamondback.com

Silky-smooth tandem tubes

Santana Exogrid Team Scandium: Two-seater with a "bifusion" frame made by infusing a cut-out aluminum frame with carbon inserts, which greatly reduces road vibration and fatigue.

Likes: Tandems can go super-fast, but the long expanses of strengthened tubing also transmit a lot of vibration. High-end maker Santana smoothes the rattling ride by inserting a carbon-fiber sleeve into an aluminum, titanium or steel tube. That causes "bilateral dampening," in which the vibrational frequencies of the different materials cancel each other out. Bifusion is used in the two strongest tubes of a tandem — the downtube and the bottom tube — with metal sections that are laser-cut and infused with carbon. In a four-hour test of two nearly identical Santanas two weeks ago, my 15-year-old son (and frequent tandem partner), Joey, and I found the Exogrid Team Scandium (aluminum) model significantly smoother than the regular Team Scandium. That would translate into much less fatigue over an all-day or weeklong trip.

Dislikes: Even for notoriously expensive high-end tandems, Bifusion tubing is hideously pricey, adding $2,000 to the cost of any of Santana's regular "Team" tandems.